It is known from the applicant's own patent application WO-2008/007024, a device having a reactive type antenna element surrounded by a plurality of metallic diffusers. Thanks to this arrangement, the electromagnetic wave is focused to a point i near the antenna element at a sub wavelength distance.
This device is efficient, but is limited to the focalisation of a wave to the core of the reactive antenna element, that is to say to only one single point at a short distance from the metallic diffusers.